GREENBOX Horticulture, an Alternative Avenue of Urban Food Production

Abstract

In response to the pressure on food security caused by rising global population and urbanization, the Yang Laboratory at the University of Connecticut has developed the so-called GREENBOX technology that allows crop growth in individual climate-controlled boxes in urban warehouse environments and other enclosed structures. A GREENBOX unit is a thermally insulated modular structure with LED artificial lighting, soilless (hydroponic) cultivation platform, and complete environmental controls. Multiple GREENBOX units can be integrated into a large production system at various scales. This study evaluated the applicability of the GREENBOX technology in the urban warehouse environment by studying the environmental parameters and productivity. We carried greenhouse growth simultaneously for reference. We grew Butterhead Rex lettuce (Lactuca sativa) over 30-day growing cycles in summer (July-August, 2020) and winter (December, 2020-January, 2021) in an experimental greenhouse and two protocol GREENBOX units located in the high ceiling headhouse of the experimental greenhouse at Storrs, Connecticut. We collected environmental data, including light, temperature, and relative humidity and crop growth data, including wet and dry biomass in the two production systems. Descriptive statistics were used to describe the environmental and biomass data. Results indicated that the GREENBOX could provide desired environmental conditions to sustain crop growth over summer and winter. The Daily Light Integral, controllable at the grower’s discretion, in the GREENBOX, ranged between 32.48 - 36.70 mol/m2·d at crop canopy height. The mean daily temperature and relative humidity in the GREENBOX fell within the optimal ranges of 17˚C - 29˚C and 40% - 60%, respectively. Regardless of seasons, lettuce crops were all healthy and grew to full size over the 30-day cycle. Measured productivity followed similar patterns, similar across both growing locations but higher over summer than winter for both systems. Our study indicated that the GREENBOX technology has a high potential in urban horticulture because it does not require arable land like greenhouses and can utilize existing urban structures for sustainable food production.